*{box-sizing:border-box}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans SC","PingFang SC","Hiragino Sans GB",sans-serif;margin:0;color:#0f172a;background:#0b1020}
header.app-header{position:sticky;top:0;z-index:10;background:#0b1020;border-bottom:1px solid #1f2a44;padding:12px 16px}
.brand{display:flex;align-items:center;gap:12px}
.logo{width:40px;height:40px;border-radius:12px;background:linear-gradient(135deg,#38bdf8,#818cf8);display:flex;align-items:center;justify-content:center;font-weight:900;color:white}
.titles h1{margin:0;font-size:20px;color:#e2e8f0}
.subtitle{margin:2px 0 0 0;color:#94a3b8;font-size:12px}
.controls{margin-top:10px;display:flex;flex-wrap:wrap;gap:8px}
.tab-btn,.ghost,.primary,.danger{padding:8px 12px;border-radius:10px;border:1px solid #243656;background:#0e172a;color:#e2e8f0;cursor:pointer}
.tab-btn.active,.primary{background:#1e293b;border-color:#334155}
.ghost{opacity:.9}
.danger{border-color:#dc2626;color:#fecaca}
main{padding:16px}
.view{display:none}
.view.active{display:block}
.toolbar{background:#0e172a;border:1px solid #1f2a44;border-radius:12px;padding:12px;margin-bottom:16px}
.toolbar .row{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin:6px 0}
.toolbar input,.toolbar select{padding:8px;border-radius:8px;border:1px solid #334155;background:#0b1324;color:#e2e8f0}
.hint{color:#64748b;font-size:12px}
.panel{background:#0e172a;border:1px solid #1f2a44;border-radius:12px;padding:12px}
.statusbar{display:flex;align-items:center;justify-content:space-between;color:#94a3b8;margin-bottom:10px}
.card{background:#0b1324;border:1px solid #1f2a44;border-radius:12px;padding:16px;color:#e2e8f0;min-height:180px}
.q-title{font-weight:700;margin:0 0 8px 0}
.q-meta{color:#94a3b8;font-size:12px;margin-bottom:8px}
.options{display:grid;gap:8px;margin-top:10px}
.opt{display:flex;gap:8px;align-items:flex-start;border:1px solid #334155;border-radius:10px;padding:10px;cursor:pointer;background:#0e172a}
.opt.correct{border-color:#16a34a}
.opt.wrong{border-color:#ef4444}
.opt input{margin-top:4px}
.answer{margin-top:10px;color:#a7f3d0;display:none}
.answer.show{display:block}
.nav{display:flex;gap:8px;margin-top:12px}
.summary{margin-top:12px;padding:12px;border:1px dashed #334155;border-radius:10px;color:#e2e8f0}
footer{border-top:1px solid #1f2a44;color:#94a3b8;padding:16px;text-align:center}
.flashcard{background:#0b1324;border:1px solid #1f2a44;border-radius:16px;padding:24px;color:#e2e8f0;min-height:160px}
.flashcard .front{font-weight:700;margin-bottom:10px}
.list .item{border:1px solid #334155;border-radius:10px;padding:12px;margin:8px 0;background:#0b1324}
.formula{border:1px solid #334155;border-radius:10px;padding:12px;margin:10px 0;background:#0b1324;color:#ffffff}
.formula h4{margin:0 0 6px 0}
kbd{border:1px solid #475569;border-bottom-width:2px;border-radius:6px;padding:2px 6px;background:#0e172a;color:#e2e8f0}